The present invention relates generally to mechanical presses or to any press with a sealed drive piston, and in particular, to an oil mist eliminator in an oil control system which prevents lubricating oil from leaking onto and contaminating the product stamped by the press die.
Mechanical presses, for example, straight side and gap frame stamping and drawing presses, comprise a frame having a crown and bed and a slide supported within the frame for motion toward and away from the bed. Between the slide and bed is located the press die within which a product is stamped or drawn. The slide is driven by a crankshaft having a connecting arm connected to the slide. Such mechanical presses are widely used for stamping and drawing operations and vary substantially in size and available tonnage depending upon the intended use.
In most cases, lubricating oil within the press drive, through gravity and open areas in the press crown, moves down onto the slide and ultimately migrates toward the press die. This oil can find its way to the product being worked upon in the press. If the workpiece becomes contaminated with oil, it may be rejected and scrapped, thereby increasing production costs. This is an important issue in industries dealing with food and beverage containers.
Certain prior art presses have been designed with pistons which protrude from the bottom of the crown. The slide is attached to these pistons which are in turn connected to the press drive for reciprocation. Seals installed about these pistons seal the oil within the crown and keep it from contaminating the workpieces. This oil control means is passive, and works only while the seal maintains its integrity. Seal damage due to installation, contamination, corrosion, or seal compression either occur rapidly or eventually, degrading the seals' ability to retain oil within the crown. Eventually, an oil leak occurs that allows oil to reach the stamped workpieces, thus ruining the product and increasing production costs.
Other prior art oil control systems utilize a filter upstream of the pump suction port. A disadvantage of this arrangement is that since the filter is on the vacuum side of the pump, the filter cannot be drained while the pump is in operation. The oil control system must be shut off to discharge the pump because ambient air simply runs up the filter drain, if any, and prevents the oil from draining out of the filter.